London Evening Standard/London

The number of MPs employing family members has soared by nearly a fifth in a year.

Despite fury over parliamentary expenses, 155 MPs – nearly one in four – now have wives, children and even parents on the public payroll.

The relatives enjoy salaries as high as £50,000 for office duties – costing taxpayers £4mn last year.

Among senior Tories enjoying the perk are Justice Secretary Chris Grayling, Transport Secretary Patrick McLoughlin, Chief Whip Sir George Young and Environment Secretary Owen Paterson.

The latter two are millionaires and earn more than £130,000 a year.

Michael Moore, the Liberal Democrat Scottish Secretary, employs his wife as a case worker. The bill for MPs’ expenses rose by an inflation-busting 7% despite David Cameron’s pledge to bring down the cost of politics.

The 17% rise in family employment reflects a rule change that allows MPs to spend more on staff and, by using relatives, top up their household income.

In 2011-12 they were allowed to claim only £115,000 a year for staff. But that was increased in 2012-13 to £144,000 for London MPs to reflect higher costs in the capital.

Other MPs claim up to £137,000.

Expenses – office outlays and personal costs such as travel and accommodation – were up from £91.5mn in 2011-12 to £98mn, according to the Independent Parliamentary Standards Authority.

Spending is now higher than in the run-up to the expenses scandal of 2009.

Matthew Sinclair of the TaxPayers’ Alliance said: “Any politician using taxpayers’ money to employ a relative must be completely open about who is being paid, how much and for what. “And in the light of past abuses, they shouldn’t be surprised when their constituents demand more openness if they fail to give a detailed explanation as to how they are spending that cash.”

The public outcry over MPs employing family members began in 2008, when Tory MP Derek Conway was accused of paying his two sons for non-existent jobs. Calls for the rules to be changed intensified after the expenses scandal broke a year later.

Other ministers who employ relatives include Alistair Burt and Hugo Swire from the Foreign Office, Business Minister Michael Fallon, Stephen Hammond at the department for transport, and Northern Ireland minister Mike Penning. Analysis of the expenses claims made over the year 2012-13 show the largest was from Ian Paisley, DUP member for North Antrim.

His claim was for £100,204  - largely due to travel costs. Ipsa claimed it had saved the taxpayer £35mn since taking over the expenses system in 2010. However, it used figures from two years before it started work – and before the expenses scandal – as a baseline.

The figures come after the watchdog proposed lifting pay from £66,000 now to £74,000 after the 2015 general election.